KR101689312B1 - Improved packaging for led combinations - Google Patents

Abstract

In summary, the present invention is directed to devices, systems, methods, and computer programs that enable thermally enhanced packaging of a plurality of light emitting diodes (110, 112, 114) and at least one integrated circuit (116). The light emitting diode 110 most sensitive to temperature among the plurality of light emitting diodes is disposed between the at least one integrated circuit and light emitting diodes 112 and 114 less sensitive to temperature among the plurality of light emitting diodes. Also, various additional measures, such as, for example, altering at least one mounting area 102, 104, 106 of at least one light emitting diode, providing at least one heat shield 118 to optimize thermal packaging, Can be taken.

Description

IMPROVED PACKAGING FOR LED COMBINATIONS < RTI ID = 0.0 >

The present invention generally relates to devices, systems, methods, and computer programs that enable thermally enhanced packaging of a plurality of light emitting diodes (LEDs). More particularly, the present invention relates to devices, systems, methods, and computer programs that enable thermally enhanced packaging of multiple LEDs and integrated circuits (ICs).

When packaging the red (R), green (G), and blue (B) LEDs together in an ultra-thin leadless package (UTLP) or other small package with a small footprint (miniaturization is preferred, (because the etendue is better), the LEDs will thermally influence each other. This is especially a problem for red LEDs because they are sensitive to high temperatures. Thus, it would be useful to have a package technology that allows to protect temperature sensitive LEDs, for example in the case of high temperatures resulting from driving LEDs at high currents.

It may be desirable to include a driver IC in an LED package (called an optical SiP) as it goes along a functional integration roadmap. ICs typically suffer from too high ambient temperatures. If an IC operating at high temperatures is required, the cost goes up sharply. Thus, in this case, operating the LEDs at a high temperature (which may be the result of driving the LEDs at high currents) allows the IC (s) within the same package to operate at a low (within their working temperature specifications) (Lower) < / RTI >

The above fact also suggests that when packaging LEDs emitting light of the same color, for example, red LEDs, green LEDs, blue LEDs or monochromatic light emitted by blue or ultraviolet LEDs, Such as direct white conversion LEDs, which emit white light by converting the white light into broad spectrum white light. When combining LEDs and driver ICs that emit light of the same color, the LEDs may have the same temperature characteristics, but the IC should still be kept at a lower temperature level.

SUMMARY OF THE INVENTION [

It is an object of the present invention to alleviate at least some of the problems described above.

This object can be achieved by a device according to claim 1, a system according to claim 13, a method according to claim 14 and a computer program according to claim 15.

Accordingly, an apparatus is provided in the first aspect of the present invention. The apparatus includes at least one mounting region, a plurality of light emitting diodes mounted on the at least one mounting region and configured to emit light of a particular color, and a plurality of light emitting diodes mounted on the at least one mounting region, And at least one integrated circuit configured to drive at least one. The light emitting diode most sensitive to temperature among the plurality of light emitting diodes may be disposed between the at least one integrated circuit and light emitting diodes less sensitive to temperature among the plurality of light emitting diodes. Thus, the at least one integrated circuit can be prevented from being disposed directly beside the light emitting diodes operating at higher temperatures with higher temperature limits. Thus, the at least one integrated circuit may be protected and maintained at lower temperatures within its working temperature specification.

In a second aspect of the present invention, the plurality of light emitting diodes may be mounted on at least two different sized mounting areas. By mounting the light emitting diodes, which are operable at higher temperatures, on larger mounting areas that allow improved heat dissipation, the heat generated by each light emitting diode can be efficiently dissipated. This second aspect can be combined with the first aspect.

In a third aspect of the present invention, the plurality of light emitting diodes may be mounted on at least one mounting area separated from at least one mounting area on which the at least one integrated circuit is mounted. Thus, the hot portion of the device including the plurality of light emitting diodes can be separated from the cool portion of the device including the at least one integrated circuit. Thus, the at least one integrated circuit can be protected from higher temperatures. This third aspect may be combined with any of the previous aspects.

In a fourth aspect of the present invention, the apparatus may include at least one thermal shielding disposed between the plurality of light emitting diodes and the at least one integrated circuit. The shield may protect the at least one integrated circuit from heat generated by the light emitting diodes. Thus, the at least one integrated circuit can be protected from heat. This fourth aspect may be combined with any of the previous aspects.

In a fifth aspect of the present invention, the apparatus may include at least one thermal conductor disposed between the plurality of light emitting diodes and the at least one integrated circuit and configured to transmit heat. The thermal conductor may provide additional heat transfer in the apparatus. Therefore, the heat can be efficiently dissipated. This fifth aspect may be combined with any of the previous aspects.

In a sixth aspect of the present invention, the apparatus may comprise at least one heat shield disposed between at least one of the temperature sensitive light emitting diode and the temperature sensitive light emitting diode. In this way, light-emitting diodes that are most sensitive to temperature can be protected from heat generated by light-emitting diodes that are less sensitive to temperature. Thus, the latter thermal influence on electrons can be reduced. This sixth aspect may be combined with any of the previous aspects.

In a seventh aspect of the present invention, the apparatus may comprise at least one heat shield disposed between at least two of the light-emitting diodes less sensitive to temperature. Thus, the thermal influence of the light emitting diodes, which are less sensitive to temperature, to each other can be reduced. Thus, the light emitting diodes can be thermally decoupled. This seventh aspect may be combined with any of the previous aspects.

In an eighth aspect of the present invention, at least one of the at least one mounting region may be asymmetrically shaped such that a distance between the plurality of light emitting diodes and the at least one integrated circuit is maximized. In this way, the at least one integrated circuit may be arranged as far as possible from the light emitting diodes. Therefore, the influence of the heat generated by the light emitting diodes can be reduced. This eighth aspect may be combined with any of the previous aspects.

In a ninth aspect of the present invention, the apparatus may comprise a structure comprising at least one material and surrounding the plurality of light emitting diodes and the at least one integrated circuit, the structure comprising at least And may include two sections. Thus, heat transfer at any location can be locally increased or decreased, depending on which component of the device is at that location. This ninth aspect may be combined with any of the previous aspects.

In a tenth aspect of the invention, the cross section of the device can be at least locally reduced. Thus, heat dissipation to the outside of the apparatus can be improved. This tenth aspect may be combined with any of the previous aspects.

In an eleventh aspect of the present invention, the apparatus includes at least one ring-like structure configured to thermally shield at least one of the plurality of light emitting diodes and / or the at least one integrated circuit . Thus, the specific components of the device can be protected from the heat generated by its other components. This eleventh aspect may be combined with any of the previous aspects.

In a twelfth aspect of the present invention, the apparatus comprises at least one ring-shaped heat sink configured to dissipate heat generated by at least one of the plurality of light emitting diodes and / or the at least one integrated circuit ). In this way, the heat generated by the components of the apparatus can be efficiently dissipated. This twelfth aspect can be combined with any of the previous aspects.

A system is provided in the thirteenth aspect of the present invention. The system may include a board including thermal dissipation enhancing elements and at least one device according to any of the previous aspects. The at least one device may be mounted on the board. Thus, good heat transfer from the at least one device to the board and good overall thermal performance can be achieved.

A method is provided in the fourteenth aspect of the present invention. The method includes mounting a plurality of light emitting diodes each configured to emit light of a particular color on at least one mounting area and at least one integrated circuit configured to drive at least one of the plurality of light emitting diodes, On the mounting area of the first substrate. The light emitting diode most sensitive to temperature among the plurality of light emitting diodes may be disposed between the at least one integrated circuit and light emitting diodes less sensitive to temperature among the plurality of light emitting diodes. Thus, the at least one integrated circuit can be prevented from being disposed directly beside the light emitting diodes operating at higher temperatures with higher temperature limits. Thus, the at least one integrated circuit may be protected and maintained at lower temperatures within its working temperature specification.

In a fifteenth aspect of the present invention, a computer program is provided. The computer program may comprise program code means for causing the computer to perform the steps of the method according to the fourteenth aspect when executed on the computer. Therefore, the same rights as the method according to the fourteenth aspect can be obtained.

Other advantageous modifications are defined in the dependent claims.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter with reference to the accompanying drawings.
1 shows a schematic diagram showing an arrangement of an exemplary apparatus according to an embodiment.
Figure 2 shows a schematic plan view of an exemplary device according to the embodiment shown in Figure 1;
Figure 3 shows a schematic perspective view of an exemplary apparatus according to an embodiment mounted on a board.
Figure 4 shows a flow diagram illustrating the basic steps of an exemplary method according to an embodiment.
Figure 5 shows an example of a software-based implementation of an embodiment.

FIG. 1 shows a schematic diagram illustrating an arrangement of an exemplary apparatus 100 according to an embodiment. The device 100 may be any kind of ultra-thin leadless package (UTLP) or other small package. It may include a first mounting area 102, a second mounting area 104, a third mounting area 106, and a fourth mounting area 108. It may also include a red (R) light emitting diode (LED) 110, a green (G) LED 112, a blue (B) LED 114, and an integrated circuit (IC) IC 116 may be an application-specific integrated circuit (ASIC), which may include, for example, a thermal sensor. The device 100 can include a structure 124 that includes at least one material such as a shield 118, a plurality of contact pads 120, a plurality of connectors 122, have.

The red LED 110, the green LED 112 and the blue LED 114 may be mounted on the first, second and third mounting regions 102, 104 and 106, respectively. These mounting areas may be referred to as LED die pads. The IC 116 may be mounted above the fourth mounting area 108. This mounting area can be referred to as an IC pad. Each of the LEDs 110, 112, 114 and IC 116 may be connected to the contact pads 120 by connectors 122, such as, for example, thin wires. Only some of these components are shown in FIG.

Although the individual mounting regions for each of the LEDs 110, 112, 114 and IC 116 are shown in Figure 1, other configurations are possible. For example, two or more of the LEDs 110, 112, 114 may be mounted above the common mounting area. Also, one or more of the LEDs 110, 112, 114 and the IC 116 may be mounted above the common mounting area. In addition, there may be four or more LEDs and / or multiple ICs.

Each of the LEDs 110, 112, and 114 may emit light of a specific color. They can together form an RGB light source. The LEDs 110, 112, 114 may be driven by the IC 116. That is, the IC 116 may control the currents used to drive the LEDs 110, 112, 114. There can be multiple ICs, each of which can control one or more LEDs.

1, the red LED 110 may be disposed between the green and blue LEDs 112, 114 on the one hand and the IC 116 on the other hand. The red LED 110 is sensitive to high temperatures. That is, the red LED 110 is the temperature-sensitive LED among the plurality of LEDs 110, 112, and 114, and the green and blue LEDs 112 and 114 are the ones among the plurality of LEDs 110, LEDs that are less sensitive to temperature.

If IC 116 is not some kind of IC capable of operating at high temperatures, it suffers from too high an ambient temperature. By placing the red LED 110 operating at a lower temperature between the IC 116 and the other LEDs 112 and 114 operating at a higher temperature, Lt; RTI ID = 0.0 > temperatures. ≪ / RTI >

UTLP is a package that already has good heat transfer to the board (because the LEDs are attached directly to the (large) portion of the footprint). However, the packaging described above enables a thermally improved device or package.

Various other measures may be taken to provide more improved packages, i.e., to thermally optimize packaging. For example, die pads, footprints, and additional (possibly dummy) pads may be modified / designed within the design rules of UTLP packaging technology so that heat shielding between components within the package can be improved. In the following, specific measures are described in more detail.

As shown in Figure 1, the first, second, third and fourth mounting regions 102, 104, 106 and 108, i.e., LED die pads and IC pads, May be formed asymmetrically so that the distance to the portion is optimized. In this way, temperature sensitive components such as, for example, IC 116 can be protected from heat generated by LEDs 110, 112 and 114. Conventional designs of semiconductors are straight symmetrical designs. They do not provide such an effect.

Also, as shown in FIG. 1, some LED die pads may be made larger than others, so that the heat generated at one location does not affect or otherwise affect other parts of the device 100. have. That is, the first mounting area 102 for the temperature-sensitive red LED 110 includes the second and third mounting areas 104 and 106 for the less sensitive green and blue LEDs 112 and 114, Lt; / RTI > Thus, the first mounting area 102 can provide improved heat dissipation compared to the second and third mounting areas 104, 106. Thus, the temperature sensitive red LED 110 can be protected and maintained at temperatures within its operating temperature specification. That is, the footprints can be modified / designed such that heat shielding between the components of the device 100 can be improved.

(Un-occupied, or a "dummy" thereon), a shielding die or a heat sink (not shown) so that the heat generated at one location will not affect or otherwise affect other portions of the device 100. [ Additional pads may be provided. For example, first, second and third mounting regions 102, 104, 106, red, green and blue LEDs 110, 112, 114 and associated contact pads 120 and connectors 122 ) And the cool portion of the device 100, including the fourth mounting area 108, the IC 116 and the associated contact pads 120 and connectors 122, A shield 118 may be provided. The shield 118 may be, for example, a metal elongated " die "serving as a heat" wall ". It can separate the hot portion of the device 100 from its cool portion (i. E., "Thermally isolate" those portions). Thus, the IC 116 can be protected from too high a temperature. The shield 118 may also comprise or be comprised of any type of thermal conductor, such as a protruding thermal conductor or dummy die, for transferring heat. Such a thermal conductor may provide additional heat transfer in the device 100 (i.e., it may enable efficient heat dissipation). That is, either or both of the thermal walls and the thermal conductor may be disposed between the hot and cool portions of the device 100. Thermal walls can protect cool parts from heat, and thermal conductors can dissipate heat.

Figure 2 shows a schematic plan view of an exemplary device according to the embodiment shown in Figure 1; 2 is a schematic diagram of a light emitting device 100 provided between the red LED 110 mounted on the first mounting area 102 and the green and blue LEDs 112 and 114 mounted on the second and third mounting areas 104 and 106, A shield 126 is shown. This shield 126 can protect the temperature sensitive LED, i.e. the red LED 110, from the heat generated by less temperature sensitive LEDs, i.e., green and blue LEDs 112 and 114 . Thus, the latter thermal influence on electrons can be reduced. Although a shield over both green and blue LEDs 112 and 114 is shown in FIG. 2, other configurations are possible. For example, a shield may be provided between the red LED 110 and only one of the green and blue LEDs 112, 114.

2 also shows the shield 128 provided between the green LED 112 mounted on the second mounting area 104 and the blue LED 114 mounted on the third mounting area 106. In this embodiment, This shield 128 may reduce the thermal affects of the LEDs 112, 114, which are less sensitive to temperature, to each other. Thus, these LEDs can be thermally isolated.

Within material boundary conditions and design rules, it is also possible to design / form "ring-shaped" structures for shielding certain parts. Even a ring-shaped "dummy" heat sink may be provided to the device 100. [ For example, as shown in FIG. 2, a ring-shaped structure 130 surrounding IC 116 may be part of device 100. The ring-shaped structure 130 may protect the IC 116 from heat generated by the LEDs 110, 112, 114. Furthermore, a ring-shaped heat sink 132 surrounding the green and blue LEDs 112, 114 may be part of the device 100, as also shown in FIG. Shaped heat sink 132 can efficiently dissipate the heat generated by the LEDs 112 and 114 less sensitive to this temperature.

Although only the ring-shaped structure 130 in IC 116 is shown in Fig. 2, alternative configurations can be envisaged. For example, a ring-shaped structure surrounding the red LED 110 may be provided. Such a ring-like structure can prevent the red LED 110 from suffering from too high a temperature due to the heat generated by the green and blue LEDs 112, 114. Also, ring-shaped heat sinks 132 and other types of heat sinks may be considered in the green and blue LEDs 112, 114. For example, a ring-shaped heat sink surrounding the red LED 110 may be provided. Such a ring-shaped heat sink can efficiently dissipate the heat generated by the red LEDs 110.

Another approach consists in (perhaps locally) adapting the structure 124 surrounding the LEDs 110, 112, 114 and the IC 116 such that heat transfer is locally increased or decreased. That is, the structure 124 may include at least two sections having different heat transfer characteristics. Thus, the heat transfer at any location can be locally increased or decreased depending on which component of the device is at that location. For example, the structure 124 may be designed to increase the heat transfer at the green and blue LEDs 112, 114. On the other hand, the structure 124 may have a section with a low thermal conductivity over a "thermal decoupling pad " such as, for example, Local modification of the structure 124 may be useful for LED applications because the function or device requires that the device or package be open or transparent at the locations of the LEDs and preferably the ICs are shielded from light.

Also, for improved heat transfer / shielding, the lead frame cross section can be reduced (even locally) by modifying the lead frame material or by modifying the lead frame manufacturing method. That is, the cross-section of the device 100 may be at least locally reduced. Thus, heat dissipation to the outside of the apparatus 100 can be improved.

FIG. 3 shows a schematic perspective view of an exemplary apparatus 100 according to an embodiment mounted on a board 134. Device 100, such as, for example, an LED package, may be mounted on a printed circuit board (PCB), for example, a ceramic board, a metal core board (which may help dissipate heat), such as a resin board such as an epoxy board, . Although only one exemplary device 100 is shown in FIG. 3, there may be a plurality of exemplary devices 100 mounted on a board 134.

Connecting the device 100 to the board 134 allows for additional possibilities for thermal optimization since the connections carry heat. For example, some pads on such a device 100 may be connected to the board pads and others may be disconnected (if the function allows it). Modifying the solder pads on the board 134 is another approach. The board pads may have thermal vias to allow for increased heat transfer. Some pads of the device 100 may be connected to such board pads with thermal vias. The heat transfer from the device 100 to the board 134 can be adjusted in a desired manner by connecting only certain pads of the device 100 and / or using the board pads with thermal vias. In addition, other heat enhancing elements may be used in the board 134.

Figure 4 shows a flow diagram illustrating the basic steps of an exemplary method according to an embodiment. In step S402, a plurality of light emitting diodes each configured to emit light of a specific color may be mounted on at least one mounting area. At step S404, at least one integrated circuit configured to drive at least one of the plurality of light emitting diodes may be mounted on the at least one mounting area, and the light emitting diode most sensitive to temperature among the plurality of light emitting diodes And may be disposed between the at least one integrated circuit and light emitting diodes that are less sensitive to temperature among the plurality of light emitting diodes.

Figure 5 shows an example of a software-based implementation of an embodiment. Here, the device 500 may include a processing unit (PU) 502, and the PU 502 may be provided on a single chip or chip module, Lt; RTI ID = 0.0 > control unit < / RTI > Program code instructions may be fetched from the MEM 504 and loaded into the control unit of the PU 502 to perform processing steps such as those described in connection with FIG. The processing steps can be performed based on the input data DI and generate the output data DO. The input data DI may indicate information about the position of components, for example, and the output data DO may indicate an instruction for the mounting machine, for example.

As described above, the device 100 may be a UTLP package. That is, it can follow the design rules of UTLP packaging technology. The overall width of the device 100 may be, for example, 1.65 mm. For example, the die pad thickness may be 62 [mu] m and the contact pad thickness may be 25 [mu] m. The minimum distance between the pads may be, for example, 100 [mu] m. An effective heat transfer coefficient of 15 W / m < ² > K (standard environment) can be generated outside the device 100, for example. If the device 100 is mounted on a board, such as the board 134, the effective heat transfer coefficient at the contacts between the device 100 and the board depends on the configuration of the board. In a simple, non-thermally optimized board, the effective heat transfer coefficient may be, for example, 200 W / m ² K. For example, in a board having relatively large copper areas, such as a board with a single copper layer, the effective heat transfer coefficient may be, for example, 500 W / m ² K. The effective heat transfer coefficient in a thermally enhanced board (via, double layer, etc.) may be, for example, 1000 W / m ² K. These parameters are to be regarded as illustrative only and not restrictive.

In summary, the present invention is directed to an apparatus, system, method and computer program that enable thermally enhanced packaging of a plurality of light emitting diodes and at least one integrated circuit. A light emitting diode most sensitive to temperature among the plurality of light emitting diodes is disposed between the at least one integrated circuit and light emitting diodes less sensitive to temperature among the plurality of light emitting diodes. In addition, various additional measures can be taken to thermally optimize the packaging, such as changing at least one mounting area of at least one light emitting diode, providing at least one heat shield, and the like.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be regarded as illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments.

Modifications to the embodiments disclosed by those skilled in the art in carrying out the claimed invention may be understood and effected from a study of the drawings, specification, and appended claims.

In the claims, the word " comprising "does not exclude other elements or steps, and the word" a " A single processor or other unit may fulfill the functions of some of the items described in the claims. The mere fact that certain measures are recited in different dependent claims does not indicate that a combination of these measures can not be used to advantage.

A computer program that can control the processor to perform the claimed features may be stored / distributed on a suitable medium such as an optical storage medium or a solid state medium provided with other hardware or as part of another hardware, but in other forms, May be distributed over the Internet or other wired or wireless communication systems. It can be used in conjunction with a new system, but it may also be applied when upgrading or upgrading existing systems to enable existing systems to execute the claimed features.

A computer program product for a computer may include portions of software code for performing processing steps such as those described, for example, in connection with FIG. 4 when the computer program product is run on a computer. The computer program product may further comprise a computer readable medium having stored therein the software code portions, such as, for example, an optical storage medium or a solid state medium.

Any reference signs in the claims shall not be construed as limiting the scope thereof.

Claims (15)

A plurality of mounting areas (102, 104, 106, 108);
A plurality of light emitting diodes (110, 112, 114) each mounted on a first one of the plurality of mounting areas and configured to emit light of a particular color; And
At least one integrated circuit (116) mounted on a second mounting area different from the first mounting area of the plurality of mounting areas and configured to drive at least one of the plurality of light emitting diodes,
Lt; / RTI >
The light emitting diode 110 most sensitive to temperature among the plurality of light emitting diodes is disposed between the at least one integrated circuit and light emitting diodes 112 and 114 less sensitive to temperature among the plurality of light emitting diodes,
The plurality of light emitting diodes being mounted on at least two different sized mounting areas,
Wherein the mounting region for the light-emitting diode most sensitive to the temperature is greater than the mounting regions for light-emitting diodes less sensitive to the temperature. delete The method according to claim 1,
Wherein the plurality of light emitting diodes are mounted on at least one mounting area (102, 104, 106) separated from at least one mounting area (108) on which the at least one integrated circuit is mounted. The method according to claim 1,
And at least one thermal shielding (118) disposed between the plurality of light emitting diodes and the at least one integrated circuit. The method according to claim 1,
And at least one thermal conductor (118) disposed between the plurality of light emitting diodes and the at least one integrated circuit and configured to transfer heat. The method according to claim 1,
And at least one heat shield (126) disposed between at least one of the temperature sensitive light emitting diode and the temperature sensitive light emitting diode. The method according to claim 1,
And at least one heat shield (128) disposed between at least two of the temperature sensitive light emitting diodes. The method according to claim 1,
Wherein at least one of the plurality of mounting regions is asymmetrically shaped such that a distance between the plurality of light emitting diodes and the at least one integrated circuit is maximized. The method according to claim 1,
And a structure (124) comprising at least one material and surrounding said plurality of light emitting diodes and said at least one integrated circuit,
Wherein the structure comprises at least two sections having different heat transfer characteristics. The method according to claim 1,
And at least one ring-like structure (130) configured to thermally shield at least one of the plurality of light emitting diodes and / or the at least one integrated circuit. The method according to claim 1,
And at least one ring-shaped heat sink (132) configured to dissipate heat emitted by at least one of the plurality of light emitting diodes and / or the at least one integrated circuit. A board 134 including thermal dissipation enhancing elements; And
12. Device according to any one of the claims 1 to 11, characterized in that it comprises at least one device
Lt; / RTI >
Wherein the at least one device is mounted on the board. Mounting a plurality of light emitting diodes each configured to emit light of a specific color on a first one of the plurality of mounting areas (S402); And
Mounting (S404) at least one integrated circuit configured to drive at least one of the plurality of light emitting diodes on a second one of the plurality of mounting areas, the second mounting area being different from the first mounting area;
Lt; / RTI >
Wherein the temperature sensitive light emitting diode among the plurality of light emitting diodes is disposed between the at least one integrated circuit and light emitting diodes less sensitive to temperature among the plurality of light emitting diodes,
The plurality of light emitting diodes being mounted on at least two different sized mounting areas,
Wherein the mounting region for the light-emitting diode that is most sensitive to the temperature is greater than the mounting regions for light-emitting diodes that are less sensitive to the temperature. And program code means for causing the computer to perform the steps of the method according to claim 13 when the computer program is run on the computer. delete

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